BACKGROUND: In primary care, where the majority of prescribing occurs, only 4% to 21% of patients achieve the optimum benefit from their medications. As experts in drug therapy, clinical pharmacists are well-positioned to improve the quality of medication use in VHA primary care. Under the Patient Aligned Care Team (PACT) model, however, a single pharmacist is assigned to more than 5,000 patients and cannot possibly review each patient's medication regimen at each visit. Thus, the effort of PACT pharmacists must be targeted to patients for whom the likelihood of benefit is greatest. THE TRIAGE ALGORITHM FOR PACT PHARMACY SERVICES (TAPPS): TAPPS is a novel health informatics tool that we developed to provide PACT pharmacists with concise real-time clinical reports to facilitate decisions about which patients are most likely to benefit from their services. Our approach is consistent with key PACT principles, where pharmacists contribute to team-based care by directly taking responsibility for patient outcomes, practicing at the top of their license, enhancing access, and leveraging health information technology to increase efficiency. TAPPS may be particularly beneficial for rural veterans, as patients engaged in primary care at rural VHA clinics are nearly 50% less likely to receive clinical pharmacy services than patients in primary care at a VHA medical center. RESEARCH PLAN: Aim 1 will test the utility of TAPPS by independently evaluating its 3 key innovations in 3 separate projects involving real-world primary care patients. Aim 2 will determine TAPPS effectiveness using a stepped wedge cluster randomized trial design. The study will involve 25 PACT pharmacists across 5 medical centers. All pharmacists will begin in the control condition (no access to TAPPS clinical reports) and randomly selected groups of pharmacists will be switched over to the intervention condition (full access to TAPPS reports) in successive 10-week time blocks, such that all pharmacists will be in the intervention condition by the end of the study. Aim 3 will gather qualitative interviews from PACT pharmacists involved in the stepped wedge trial after they have completed their first 10-week block of TAPPS use, with a repeated interview after their third 10-week block. The goal of these interviews is to assess both positive and negative effects of TAPPS on patient care and identify potential barriers to implementation. If TAPPS is proven effective, our findings will be used to make refinements to the TAPPS system and to design a subsequent national implementation study. IMPLICATIONS: TAPPS has the potential for significant impact on the health of veterans by enabling PACT pharmacists to minimize risk for adverse drug events and seek the full benefit of prescription medications. If proven effective, national implementation of TAPPS could affect all VHA primary care patients, with particular benefits for rural veterans. Our experience with TAPPS also has important implications outside VHA, including how medication therapy management services are delivered to Medicare Part D beneficiaries.